TOLEDO, Ohio  In the beginning she was known, simply, as Hull 301. Powered by a Westinghouse double-reduction, cross-compound, steam turbine with two coal-fired water-tube boilers, she measured 729 feet in length. Launched in River Rouge, Mich., in 1958, her most fateful journey occurred 17 years later when, loaded with 26,116 tons of taconite ore pellets, she headed for Toledo before encountering 70-knot winds and 25-foot waves.

The Great Lakes freighter known as the S.S. Edmund Fitzgerald sank 40 years ago Tuesday, launching one of the greatest maritime mysteries of all time and inspiring the greatest shipping song of the modern age. Today the whole English-speaking world knows the single element of the Edmund Fitzgerald saga that has won universal agreement, which is that the lake never gives up her dead when the skies of November turn gloomy.

This disaster at the distended thumb of Lake Superior permitted the phrase "The Wreck of the Edmund Fitzgerald" to replace "The Wreck of the Hesperus" in North American seafaring folklore. Indeed, the displacement of Henry Wadsworth Longfellow by Gordon Lightfoot, and the disappearance from the American canon of Longfellow's 1842 Hesperus poem ("Colder and louder blew the wind, / A gale from the Northeast, / The snow fell hissing in the brine, / And the billows frothed like yeast," lines once memorized by American schoolchildren) are only two indications of the immense cultural power possessed by the destruction, in Canadian waters 17 miles north-northwest of Whitefish Point, Mich., of a lake bulk freighter with 29 souls aboard.

The wonder is that the wreck of the Edmund Fitzgerald has persisted in our culture. There have been more than 8,000 shipwrecks on the Great Lakes  an average of one every 11 days  in the last 250 years, many with far greater losses of life than the vessel known as the Mighty Fitz or, because of its favored route, the Toledo Express.

But the Great Lakes themselves have a special romance, and a special place in our history. Created in the glacial ice age 12,000 years ago, they were the setting for great dramas in American and Canadian history: the search for a route to China; the travels of the fur traders and the missionaries; the early settlements; the recurrent conflicts, with the Indians and, later, the British; the poetic development of the Erie Canal and the prosaic development of the St. Lawrence Seaway; and the daring rum-running of Prohibition.

Over the centuries, the Great Lakes have provided fresh water and hydropower, and became a shipping route for the great industrial forces that shaped the American Midwest and that made North America a manufacturing and natural-resource powerhouse. The iron, coal and oil found on its shores helped win two world wars and created the economic empires of Carnegie, Rockefeller, J.P. Morgan and Ford.

Part of the persistence of the Edmund Fitzgerald in North American memory is that the wreck occurred in a period of relative shipping tranquility on the Great Lakes. Maritime safety has come a long way since the installation of the first steam whistle on a ship in 1844 and Martha Costen's 1871 patent for maritime flares. Indeed, only 20 ships went down in the period between 1948 and 1975, and there hasn't been a major wreck since the Fitz.

A decade ago the Canadian government, regarding the area where the Edmund Fitzgerald now rests in 530 feet of water as a grave site, restricted access to the two segments of the ship, one part, 275 feet long, facing the lake surface, the other, about 253 feet long, facing the lake bottom.

Very little has been recovered, though an orange life raft and a round rescue ring are on display at the sparkling new National Museum of the Great Lakes here in Toledo. The museum has run a series of programs all summer and fall on the Edmund Fitzgerald, reflecting its status as, in the words of James Lundgren, the museum's director of operations, "one of the great mysteries of the Great Lakes."

Or, as Michael Schumacher put it in his 2005 book "The Mighty Fitz": "There were no final answers, nor would there ever be, there could only be speculation."

Today the speculation revolves around whether the Edmund Fitzgerald, once one of the largest freighters to ply the Great Lakes, collided with an underwater mountain range, or whether the boat was compromised by debris, or whether the hatches, or the hatch covers, were damaged. The hatch theory was put forward by the Coast Guard, rejected by a National Transportation Safety Board investigation and then revived by the NTSB. The debate rolls on, like the waves on Lake Superior on a particularly tumultuous day. Whatever the answer, weather played an important role.

It is true, as Mr. Lightfoot has said of the Edmund Fitzgerald, that "as the big freighters go, it was bigger than most, with a crew and good captain well seasoned." None of that mattered when it slipped from the Burlington-Northern Railroad dock in Superior, Wis., at dawn.

The Fitz traveled with another freighter, the SS Arthur M. Anderson. Soon, a cold front swept through from Canada, changing the weather and the fate of the two vessels, which became separated in the wind and cold rain. For it is true that in a storm like that, "Superior sings in the rooms of her ice-water mansion."

The Anderson's captain reported that the waves "that came across buried my entire deck in about 12 feet of water." One wave reached the bridge deck, some 35 feet above water level. There was no radio communication with the Edmund Fitzgerald after Capt. Ernest M. McSorley reported that the ship, listing to port, was taking on water, that its radar wasn't operating and that the ballast tank vent pipes were damaged. "Don't allow nobody on deck," he commanded.

The next day, in a musty old hall in Detroit  its true name is not the Maritime Sailors' Cathedral celebrated by Mr. Lightfoot but the Mariners' Church of Detroit  the church bell chimed 'til it rang 29 times, one for each man on the Edmund Fitzgerald.

David Shribman, a Pulitzer Prize winner in journalism, is executive editor of the Pittsburgh Post-Gazette.